1
|
Zhang H, Xin M, Lin L, Chen C, Balestra D, Ding Q. Pleiotropic effects of different exonic nucleotide changes at the same position contribute to hemophilia B phenotypic variation. J Thromb Haemost 2024; 22:975-989. [PMID: 38184202 DOI: 10.1016/j.jtha.2023.12.031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Revised: 12/29/2023] [Accepted: 12/29/2023] [Indexed: 01/08/2024]
Abstract
BACKGROUND The disease-causing effects of genetic variations often depend on their location within a gene. Exonic changes generally lead to alterations in protein production, secretion, activity, or clearance. However, owing to the overlap between proteins and splicing codes, missense variants can also affect messenger RNA splicing, thus adding a layer of complexity and influencing disease phenotypes. OBJECTIVES To extensively characterize a panel of 13 exonic variants in the F9 gene occurring at 6 different factor IX positions and associated with varying severities of hemophilia B (HB). METHODS Computational predictions, splicing analysis, and recombinant factor IX assays were exploited to characterize F9 variants. RESULTS We demonstrated that 5 (38%) of 13 selected F9 exonic variants have pleiotropic effects. Although bioinformatic approaches accurately classified effects, extensive experimental assays were required to elucidate and deepen the molecular mechanisms underlying the pleiotropic effects. Importantly, their characterization was instrumental in developing tailored RNA therapeutics based on engineered U7 small nuclear RNA to mask cryptic splice sites and compensatory U1 small nuclear RNA to enhance exon definition. CONCLUSION Overall, albeit a multitool bioinformatic approach suggested the molecular effects of multiple HB variants, the deep investigation of molecular mechanisms revealed insights into the HB phenotype-genotype relationship, enabling accurate classification of HB variants. Importantly, knowledge of molecular mechanisms allowed the development of tailored RNA therapeutics, which can also be translated to other genetic diseases.
Collapse
Affiliation(s)
- Huayang Zhang
- Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China; State Key Laboratory of Medical Genomics, Shanghai Institute of Hematology, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Min Xin
- Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China; State Key Laboratory of Medical Genomics, Shanghai Institute of Hematology, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Liya Lin
- Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China; State Key Laboratory of Medical Genomics, Shanghai Institute of Hematology, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Changming Chen
- Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China; State Key Laboratory of Medical Genomics, Shanghai Institute of Hematology, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Dario Balestra
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy.
| | - Qiulan Ding
- Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China; Collaborative Innovation Center of Hematology, Shanghai Jiaotong University School of Medicine, Shanghai, China.
| |
Collapse
|
2
|
Todaro AM, Radu CM, Ciccone M, Toffanin S, Serino ML, Campello E, Bulato C, Lunghi B, Gemmati D, Cuneo A, Hackeng TM, Simioni P, Bernardi F, Castoldi E. In vitro and ex vivo rescue of a nonsense mutation responsible for severe coagulation factor V deficiency. J Thromb Haemost 2024; 22:410-422. [PMID: 37866515 DOI: 10.1016/j.jtha.2023.10.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Revised: 10/10/2023] [Accepted: 10/11/2023] [Indexed: 10/24/2023]
Abstract
BACKGROUND Coagulation factor V (FV) deficiency is a rare bleeding disorder that is usually managed with fresh-frozen plasma. Patients with nonsense mutations may respond to treatment with readthrough agents. OBJECTIVES To investigate whether the F5 p.Arg1161Ter mutation, causing severe FV deficiency in several patients, would be amenable to readthrough therapy. METHODS F5 mRNA and protein expression were evaluated in a F5 p.Arg1161Ter-homozygous patient. Five readthrough agents with different mechanisms of action, i.e. G418, ELX-02, PTC-124, 2,6-diaminopurine (2,6-DAP), and Amlexanox, were tested in in vitro and ex vivo models of the mutation. RESULTS The F5 p.Arg1161Ter-homozygous patient showed residual F5 mRNA and functional platelet FV, indicating detectable levels of natural readthrough. COS-1 cells transfected with the FV-Arg1161Ter cDNA expressed 0.7% FV activity compared to wild-type. Treatment with 0-500 μM G418, ELX-02, and 2,6-DAP dose-dependently increased FV activity up to 7.0-fold, 3.1-fold, and 10.8-fold, respectively, whereas PTC-124 and Amlexanox (alone or in combination) were ineffective. These findings were confirmed by thrombin generation assays in FV-depleted plasma reconstituted with conditioned media of treated cells. All compounds except ELX-02 showed some degree of cytotoxicity. Ex vivo differentiated megakaryocytes of the F5 p.Arg1161Ter-homozygous patient, which were negative at FV immunostaining, turned positive after treatment with all 5 readthrough agents. Notably, they were also able to internalize mutant FV rescued with G418 or 2,6-DAP, which would be required to maintain the crucial platelet FV pool in vivo. CONCLUSION These findings provide in vitro and ex vivo proof-of-principle for readthrough-mediated rescue of the F5 p.Arg1161Ter mutation.
Collapse
Affiliation(s)
- Alice M Todaro
- Department of Biochemistry, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, The Netherlands
| | - Claudia M Radu
- Department of Medicine, Thrombotic and Haemorrhagic Diseases Unit, Padua University Medical School, Padua, Italy
| | - Maria Ciccone
- Department of Medical Sciences, Section of Haematology, Sant'Anna Hospital, Ferrara University, Ferrara, Italy
| | - Serena Toffanin
- Department of Medicine, Thrombotic and Haemorrhagic Diseases Unit, Padua University Medical School, Padua, Italy
| | - M Luisa Serino
- Department of Medical Sciences, Section of Haematology, Sant'Anna Hospital, Ferrara University, Ferrara, Italy
| | - Elena Campello
- Department of Medicine, Thrombotic and Haemorrhagic Diseases Unit, Padua University Medical School, Padua, Italy
| | - Cristiana Bulato
- Department of Medicine, Thrombotic and Haemorrhagic Diseases Unit, Padua University Medical School, Padua, Italy
| | - Barbara Lunghi
- Department of Life Sciences and Biotechnology, Section of Biochemistry and Molecular Biology, Ferrara University, Ferrara, Italy
| | - Donato Gemmati
- Department of Translational Medicine, Haemostasis & Thrombosis Centre, Ferrara University, Ferrara, Italy
| | - Antonio Cuneo
- Department of Medical Sciences, Section of Haematology, Sant'Anna Hospital, Ferrara University, Ferrara, Italy
| | - Tilman M Hackeng
- Department of Biochemistry, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, The Netherlands
| | - Paolo Simioni
- Department of Medicine, Thrombotic and Haemorrhagic Diseases Unit, Padua University Medical School, Padua, Italy
| | - Francesco Bernardi
- Department of Life Sciences and Biotechnology, Section of Biochemistry and Molecular Biology, Ferrara University, Ferrara, Italy
| | - Elisabetta Castoldi
- Department of Biochemistry, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, The Netherlands.
| |
Collapse
|
3
|
Testa MF, Lombardi S, Bernardi F, Ferrarese M, Belvini D, Radossi P, Castaman G, Pinotti M, Branchini A. Translational readthrough at F8 nonsense variants in the factor VIII B domain contributes to residual expression and lowers inhibitor association. Haematologica 2022; 108:472-482. [PMID: 35924581 PMCID: PMC9890017 DOI: 10.3324/haematol.2022.281279] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Indexed: 02/03/2023] Open
Abstract
In hemophilia A, F8 nonsense variants, and particularly those affecting the large factor VIII (FVIII) B domain that is dispensable for coagulant activity, display lower association with replacement therapy-related anti-FVIII inhibitory antibodies as retrieved from multiple international databases. Since null genetic conditions favor inhibitor development, we hypothesized that translational readthrough over premature termination codons (PTC) may contribute to immune tolerance by producing full-length proteins through the insertion of amino acid subset(s). To quantitatively evaluate the readthrough output in vitro, we developed a very sensitive luciferase-based system to detect very low full-length FVIII synthesis from a wide panel (n=45; ~60% patients with PTC) of F8 nonsense variants. PTC not associated with inhibitors displayed higher readthrough-driven expression levels than inhibitor-associated PTC, a novel observation. Particularly, higher levels were detected for B-domain variants (n=20) than for variants in other domains (n=25). Studies on plasma from six hemophilia A patients with PTC, integrated by expression of the corresponding nonsense and readthrough-deriving missense variants, consistently revealed higher FVIII levels for B-domain variants. Only one B-domain PTC (Arg814*) was found among the highly represented PTC not sporadically associated with inhibitors, but with the lowest proportion of inhibitor cases (4 out of 57). These original insights into the molecular genetics of hemophilia A, and particularly into genotype-phenotype relationships related with disease treatment, demonstrate that B-domain features favor PTC readthrough output. This provides a potential molecular mechanism contributing to differential PTC-associated inhibitor occurrence, with translational implications for a novel, experimentally based classification of F8 nonsense variants.
Collapse
Affiliation(s)
- Maria Francesca Testa
- Department of Life Sciences and Biotechnology and LTTA Center, University of Ferrara, Ferrara
| | - Silvia Lombardi
- Department of Life Sciences and Biotechnology and LTTA Center, University of Ferrara, Ferrara,°Current address: Department of Biotechnology and Biosciences, University of Milano-Bicocca, Milan, Italy
| | - Francesco Bernardi
- Department of Life Sciences and Biotechnology and LTTA Center, University of Ferrara, Ferrara
| | - Mattia Ferrarese
- Department of Life Sciences and Biotechnology and LTTA Center, University of Ferrara, Ferrara
| | - Donata Belvini
- Transfusion Service, Hemophilia Center and Hematology, Castelfranco Veneto Hospital, Castelfranco Veneto
| | - Paolo Radossi
- Oncohematology-Oncologic Institute of Veneto, Castelfranco Veneto Hospital, Castelfranco Veneto
| | - Giancarlo Castaman
- Center for Bleeding Disorders and Coagulation, Careggi University Hospital, Florence, Italy
| | - Mirko Pinotti
- Department of Life Sciences and Biotechnology and LTTA Center, University of Ferrara, Ferrara.
| | - Alessio Branchini
- Department of Life Sciences and Biotechnology and LTTA Center, University of Ferrara, Ferrara.
| |
Collapse
|
4
|
Lombardi S, Testa MF, Pinotti M, Branchini A. Translation termination codons in protein synthesis and disease. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2022; 132:1-48. [PMID: 36088072 DOI: 10.1016/bs.apcsb.2022.06.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Fidelity of protein synthesis, a process shaped by several mechanisms involving specialized ribosome regions and external factors, ensures the precise reading of sense as well as stop codons (UGA, UAG, UAA), which are usually localized at the 3' of mRNA and drive the release of the polypeptide chain. However, either natural (NTCs) or premature (PTCs) termination codons, the latter arising from nucleotide changes, can undergo a recoding process named ribosome or translational readthrough, which insert specific amino acids (NTCs) or subset(s) depending on the stop codon type (PTCs). This process is particularly relevant for nonsense mutations, a relatively frequent cause of genetic disorders, which impair gene expression at different levels by potentially leading to mRNA degradation and/or synthesis of truncated proteins. As a matter of fact, many efforts have been made to develop efficient and safe readthrough-inducing compounds, which have been challenged in several models of human disease to provide with a therapy. In this view, the dissection of the molecular determinants shaping the outcome of readthrough, namely nucleotide and protein contexts as well as their interplay and impact on protein structure/function, is crucial to identify responsive nonsense mutations resulting in functional full-length proteins. The interpretation of experimental and mechanistic findings is also important to define a possibly clear picture of potential readthrough-favorable features useful to achieve rescue profiles compatible with therapeutic thresholds typical of each targeted disorder, which is of primary importance for the potential translatability of readthrough into a personalized and mutation-specific, and thus patient-oriented, therapeutic strategy.
Collapse
Affiliation(s)
- Silvia Lombardi
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Milan, Italy
| | - Maria Francesca Testa
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy
| | - Mirko Pinotti
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy
| | - Alessio Branchini
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy.
| |
Collapse
|
5
|
Branchini A, Morfini M, Lunghi B, Belvini D, Radossi P, Bury L, Serino ML, Giordano P, Cultrera D, Molinari AC, Napolitano M, Bigagli E, Castaman G, Pinotti M, Bernardi F. F9 missense mutations impairing factor IX activation are associated with pleiotropic plasma phenotypes. J Thromb Haemost 2022; 20:69-81. [PMID: 34626083 PMCID: PMC9298354 DOI: 10.1111/jth.15552] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 10/06/2021] [Accepted: 10/06/2021] [Indexed: 11/30/2022]
Abstract
BACKGROUND Circulating dysfunctional factor IX (FIX) might modulate distribution of infused FIX in hemophilia B (HB) patients. Recurrent substitutions at FIX activation sites (R191-R226, >300 patients) are associated with variable FIX activity and antigen (FIXag) levels. OBJECTIVES To investigate the (1) expression of a complete panel of missense mutations at FIX activation sites and (2) contribution of F9 genotypes on the FIX pharmacokinetics (PK). METHODS We checked FIX activity and antigen and activity assays in plasma and after recombinant expression of FIX variants and performed an analysis of infused FIX PK parameters in patients (n = 30), mostly enrolled in the F9 Genotype and PK HB Italian Study (GePKHIS; EudraCT ID2017-003902-42). RESULTS The variable FIXag amounts and good relation between biosynthesis and activity of multiple R191 variants results in graded moderate-to-mild severity of the R191C>L>P>H substitutions. Recombinant expression may predict the absence in the HB mutation database of the benign R191Q/W/K and R226K substitutions. Equivalent changes at R191/R226 produced higher FIXag levels for R226Q/W/P substitutions, as also observed in p.R226W female carrier plasma. Pharmacokinetics analysis in patients suggested that infused FIX Alpha distribution and Beta elimination phases positively correlated with endogenous FIXag levels. Mean residence time was particularly prolonged (79.4 h, 95% confidence interval 44.3-114.5) in patients (n = 7) with the R191/R226 substitutions, which in regression analysis were independent predictors (β coefficient 0.699, P = .004) of Beta half-life, potentially prolonged by the increasing over time ratio between endogenous and infused FIX. CONCLUSIONS FIX activity and antigen levels and specific features of the dysfunctional R191/R226 variants may exert pleiotropic effects both on HB patients' phenotypes and substitutive treatment.
Collapse
Affiliation(s)
- Alessio Branchini
- Department of Life Sciences and Biotechnology and LTTA CentreUniversity of FerraraFerraraItaly
| | | | - Barbara Lunghi
- Department of Life Sciences and Biotechnology and LTTA CentreUniversity of FerraraFerraraItaly
| | - Donata Belvini
- Transfusion ServiceHaemophilia Centre and HaematologyCastelfranco Veneto HospitalCastelfranco VenetoItaly
| | - Paolo Radossi
- Oncohematology‐Oncologic Institute of VenetoCastelfranco Veneto HospitalCastelfranco VenetoItaly
| | - Loredana Bury
- Department of Medicine and SurgeryUniversity of PerugiaPerugiaItaly
| | - Maria Luisa Serino
- Haemostasis and Thrombosis CentreUniversity Hospital of FerraraFerraraItaly
| | - Paola Giordano
- Paediatric SectionDepartment of Biomedicine and Human OncologyA. Moro” UniversityBariItaly
| | - Dorina Cultrera
- Haemophilia Regional Reference CenterVittorio Emanuele” University HospitalCataniaItaly
| | | | - Mariasanta Napolitano
- Haematology UnitThrombosis and Haemostasis Reference Regional Center and PROMISE DepartmentUniversity of PalermoPalermoItaly
| | - Elisabetta Bigagli
- Department of Neuroscience, PsychologyDrug Research and Child Health (NEUROFARBA)Section of Pharmacology and ToxicologyUniversity of FlorenceFlorenceItaly
| | - Giancarlo Castaman
- Department of Oncology, Center for Bleeding DisordersCareggi University HospitalFirenzeItaly
| | - Mirko Pinotti
- Department of Life Sciences and Biotechnology and LTTA CentreUniversity of FerraraFerraraItaly
| | - Francesco Bernardi
- Department of Life Sciences and Biotechnology and LTTA CentreUniversity of FerraraFerraraItaly
| |
Collapse
|
6
|
Lombardi S, Aaen KH, Nilsen J, Ferrarese M, Gjølberg TT, Bernardi F, Pinotti M, Andersen JT, Branchini A. Fusion of engineered albumin with factor IX Padua extends half-life and improves coagulant activity. Br J Haematol 2021; 194:453-462. [PMID: 34109608 PMCID: PMC8362221 DOI: 10.1111/bjh.17559] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Revised: 04/21/2021] [Accepted: 04/26/2021] [Indexed: 12/29/2022]
Abstract
The short half‐life of coagulation factor IX (FIX) for haemophilia B (HB) therapy has been prolonged through fusion with human serum albumin (HSA), which drives the neonatal Fc receptor (FcRn)‐mediated recycling of the chimera. However, patients would greatly benefit from further FIX‐HSA half‐life extension. In the present study, we designed a FIX‐HSA variant through the engineering of both fusion partners. First, we developed a novel cleavable linker combining the two FIX activation sites, which resulted in improved HSA release. Second, insertion of the FIX R338L (Padua) substitution conferred hyperactive features (sevenfold higher specific activity) as for FIX Padua alone. Furthermore, we exploited an engineered HSA (QMP), which conferred enhanced human (h)FcRn binding [dissociation constant (KD) 0·5 nM] over wild‐type FIX‐HSA (KD 164·4 nM). In hFcRn transgenic mice, Padua‐QMP displayed a significantly prolonged half‐life (2·7 days, P < 0·0001) versus FIX‐HSA (1 day). Overall, we developed a novel FIX‐HSA protein with improved activity and extended half‐life. These combined properties may result in a prolonged functional profile above the therapeutic threshold, and thus in a potentially widened therapeutic window able to improve HB therapy. This rational engineering of both partners may pave the way for new fusion strategies for the design of engineered biotherapeutics.
Collapse
Affiliation(s)
- Silvia Lombardi
- Department of Life Sciences and Biotechnology and LTTA Centre, University of Ferrara, Ferrara, Italy
| | - Kristin H Aaen
- Department of Immunology, University of Oslo and Oslo University Hospital Rikshospitalet, Oslo, Norway.,Institute of Clinical Medicine and Department of Pharmacology, University of Oslo and Oslo University Hospital, Oslo, Norway
| | - Jeannette Nilsen
- Department of Immunology, University of Oslo and Oslo University Hospital Rikshospitalet, Oslo, Norway.,Institute of Clinical Medicine and Department of Pharmacology, University of Oslo and Oslo University Hospital, Oslo, Norway
| | - Mattia Ferrarese
- Department of Life Sciences and Biotechnology and LTTA Centre, University of Ferrara, Ferrara, Italy
| | - Torleif T Gjølberg
- Department of Immunology, University of Oslo and Oslo University Hospital Rikshospitalet, Oslo, Norway.,Institute of Clinical Medicine and Department of Pharmacology, University of Oslo and Oslo University Hospital, Oslo, Norway.,Department of Ophthalmology, University of Oslo and Oslo University Hospital, Oslo, Norway
| | - Francesco Bernardi
- Department of Life Sciences and Biotechnology and LTTA Centre, University of Ferrara, Ferrara, Italy
| | - Mirko Pinotti
- Department of Life Sciences and Biotechnology and LTTA Centre, University of Ferrara, Ferrara, Italy
| | - Jan T Andersen
- Department of Immunology, University of Oslo and Oslo University Hospital Rikshospitalet, Oslo, Norway.,Institute of Clinical Medicine and Department of Pharmacology, University of Oslo and Oslo University Hospital, Oslo, Norway
| | - Alessio Branchini
- Department of Life Sciences and Biotechnology and LTTA Centre, University of Ferrara, Ferrara, Italy
| |
Collapse
|
7
|
Molecular Insights into Determinants of Translational Readthrough and Implications for Nonsense Suppression Approaches. Int J Mol Sci 2020; 21:ijms21249449. [PMID: 33322589 PMCID: PMC7764779 DOI: 10.3390/ijms21249449] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Revised: 11/27/2020] [Accepted: 12/05/2020] [Indexed: 02/07/2023] Open
Abstract
The fidelity of protein synthesis, a process shaped by several mechanisms involving specialized ribosome regions and external factors, ensures the precise reading of sense and stop codons. However, premature termination codons (PTCs) arising from mutations may, at low frequency, be misrecognized and result in PTC suppression, named ribosome readthrough, with production of full-length proteins through the insertion of a subset of amino acids. Since some drugs have been identified as readthrough inducers, this fidelity drawback has been explored as a therapeutic approach in several models of human diseases caused by nonsense mutations. Here, we focus on the mechanisms driving translation in normal and aberrant conditions, the potential fates of mRNA in the presence of a PTC, as well as on the results obtained in the research of efficient readthrough-inducing compounds. In particular, we describe the molecular determinants shaping the outcome of readthrough, namely the nucleotide and protein context, with the latter being pivotal to produce functional full-length proteins. Through the interpretation of experimental and mechanistic findings, mainly obtained in lysosomal and coagulation disorders, we also propose a scenario of potential readthrough-favorable features to achieve relevant rescue profiles, representing the main issue for the potential translatability of readthrough as a therapeutic strategy.
Collapse
|
8
|
An Exon-Specific Small Nuclear U1 RNA (ExSpeU1) Improves Hepatic OTC Expression in a Splicing-Defective spf/ ash Mouse Model of Ornithine Transcarbamylase Deficiency. Int J Mol Sci 2020; 21:ijms21228735. [PMID: 33228018 PMCID: PMC7699343 DOI: 10.3390/ijms21228735] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 11/16/2020] [Accepted: 11/17/2020] [Indexed: 11/22/2022] Open
Abstract
OTC splicing mutations are generally associated with the severest and early disease onset of ornithine transcarbamylase deficiency (OTCD), the most common urea cycle disorder. Noticeably, splicing defects can be rescued by spliceosomal U1snRNA variants, which showed their efficacy in cellular and animal models. Here, we challenged an U1snRNA variant in the OTCD mouse model (spf/ash) carrying the mutation c.386G > A (p.R129H), also reported in OTCD patients. It is known that the R129H change does not impair protein function but affects pre-mRNA splicing since it is located within the 5′ splice site. Through in vitro studies, we identified an Exon Specific U1snRNA (ExSpeU1O3) that targets an intronic region downstream of the defective exon 4 and rescues exon inclusion. The adeno-associated virus (AAV8)-mediated delivery of the ExSpeU1O3 to mouse hepatocytes, although in the presence of a modest transduction efficiency, led to increased levels of correct OTC transcripts (from 6.1 ± 1.4% to 17.2 ± 4.5%, p = 0.0033). Consistently, this resulted in increased liver expression of OTC protein, as demonstrated by Western blotting (~3 fold increase) and immunostaining. Altogether data provide the early proof-of-principle of the efficacy of ExSpeU1 in the spf/ash mouse model and encourage further studies to assess the potential of RNA therapeutics for OTCD caused by aberrant splicing.
Collapse
|
9
|
Balestra D, Scalet D, Ferrarese M, Lombardi S, Ziliotto N, C. Croes C, Petersen N, Bosma P, Riccardi F, Pagani F, Pinotti M, van de Graaf SFJ. A Compensatory U1snRNA Partially Rescues FAH Splicing and Protein Expression in a Splicing-Defective Mouse Model of Tyrosinemia Type I. Int J Mol Sci 2020; 21:E2136. [PMID: 32244944 PMCID: PMC7139742 DOI: 10.3390/ijms21062136] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Accepted: 03/18/2020] [Indexed: 02/07/2023] Open
Abstract
The elucidation of aberrant splicing mechanisms, frequently associated with disease has led to the development of RNA therapeutics based on the U1snRNA, which is involved in 5' splice site (5'ss) recognition. Studies in cellular models have demonstrated that engineered U1snRNAs can rescue different splicing mutation types. However, the assessment of their correction potential in vivo is limited by the scarcity of animal models with the targetable splicing defects. Here, we challenged the U1snRNA in the FAH5961SB mouse model of hepatic fumarylacetoacetate hydrolase (FAH) deficiency (Hereditary Tyrosinemia type I, HT1) due to the FAH c.706G>A splicing mutation. Through minigene expression studies we selected a compensatory U1snRNA (U1F) that was able to rescue this mutation. Intriguingly, adeno-associated virus-mediated delivery of U1F (AAV8-U1F), but not of U1wt, partially rescued FAH splicing in mouse hepatocytes. Consistently, FAH protein was detectable only in the liver of AAV8-U1F treated mice, which displayed a slightly prolonged survival. Moreover, RNA sequencing revealed the negligible impact of the U1F on the splicing profile and overall gene expression, thus pointing toward gene specificity. These data provide early in vivo proof-of-principle of the correction potential of compensatory U1snRNAs in HTI and encourage further optimization on a therapeutic perspective, and translation to other splicing-defective forms of metabolic diseases.
Collapse
Affiliation(s)
- Dario Balestra
- Department of Life Sciences and Biotechnology, University of Ferrara, 44121 Ferrara, Italy; (D.S.); (M.F.); (S.L.); (N.Z.); (M.P.)
| | - Daniela Scalet
- Department of Life Sciences and Biotechnology, University of Ferrara, 44121 Ferrara, Italy; (D.S.); (M.F.); (S.L.); (N.Z.); (M.P.)
| | - Mattia Ferrarese
- Department of Life Sciences and Biotechnology, University of Ferrara, 44121 Ferrara, Italy; (D.S.); (M.F.); (S.L.); (N.Z.); (M.P.)
| | - Silvia Lombardi
- Department of Life Sciences and Biotechnology, University of Ferrara, 44121 Ferrara, Italy; (D.S.); (M.F.); (S.L.); (N.Z.); (M.P.)
| | - Nicole Ziliotto
- Department of Life Sciences and Biotechnology, University of Ferrara, 44121 Ferrara, Italy; (D.S.); (M.F.); (S.L.); (N.Z.); (M.P.)
| | - Chrystal C. Croes
- Tytgat Institute for Liver and Intestinal Research, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands; (C.C.C.); (N.P.); (P.B.); (S.F.J.v.d.G.)
- Department of Gastroenterology and Hepatology, Amsterdam Gastroenterology and Metabolism, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands
| | - Naomi Petersen
- Tytgat Institute for Liver and Intestinal Research, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands; (C.C.C.); (N.P.); (P.B.); (S.F.J.v.d.G.)
| | - Piter Bosma
- Tytgat Institute for Liver and Intestinal Research, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands; (C.C.C.); (N.P.); (P.B.); (S.F.J.v.d.G.)
- Department of Gastroenterology and Hepatology, Amsterdam Gastroenterology and Metabolism, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands
| | - Federico Riccardi
- Human Molecular Genetics, International Centre for Genetic Engineering and Biotechnology, 34149 Trieste, Italy; (F.R.); (F.P.)
| | - Franco Pagani
- Human Molecular Genetics, International Centre for Genetic Engineering and Biotechnology, 34149 Trieste, Italy; (F.R.); (F.P.)
| | - Mirko Pinotti
- Department of Life Sciences and Biotechnology, University of Ferrara, 44121 Ferrara, Italy; (D.S.); (M.F.); (S.L.); (N.Z.); (M.P.)
- LTTA, University of Ferrara, 44121 Ferrara, Italy
| | - Stan F. J. van de Graaf
- Tytgat Institute for Liver and Intestinal Research, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands; (C.C.C.); (N.P.); (P.B.); (S.F.J.v.d.G.)
- Department of Gastroenterology and Hepatology, Amsterdam Gastroenterology and Metabolism, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands
| |
Collapse
|
10
|
Branchini A, Pinotti M. A recoded view on the F9 p.Cys178Ter pathogenic mechanism. Thromb Res 2020; 187:88-90. [PMID: 31978811 DOI: 10.1016/j.thromres.2020.01.016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Accepted: 01/14/2020] [Indexed: 01/31/2023]
Affiliation(s)
- Alessio Branchini
- Department of Life Sciences and Biotechnology, University of Ferrara, Italy..
| | - Mirko Pinotti
- Department of Life Sciences and Biotechnology, University of Ferrara, Italy
| |
Collapse
|
11
|
Lombardi S, Ferrarese M, Marchi S, Pinton P, Pinotti M, Bernardi F, Branchini A. Translational readthrough of GLA nonsense mutations suggests dominant-negative effects exerted by the interaction of wild-type and missense variants. RNA Biol 2019; 17:254-263. [PMID: 31613176 DOI: 10.1080/15476286.2019.1676115] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Nonsense mutations are relatively frequent in the rare X-linked lysosomal α-galactosidase A (α-Gal) deficiency (Fabry disease; FD), but have been poorly investigated. Here, we evaluated the responsiveness of a wide panel (n = 14) of GLA premature termination codons (PTCs) to the RNA-based approach of drug-induced readthrough through expression of recombinant α-Gal (rGal) nonsense and missense variants.We identified four high-responders to the readthrough-inducing aminoglycoside G418 in terms of full-length protein (C56X/W209X, ≥10% of wild-type rGal) and/or activity (Q119X/W209X/Q321X, ~5-7%), resulting in normal (Q119X/Q321X) or reduced (C56X, 0.27 ± 0.11; W209X, 0.35 ± 0.1) specific activity.To provide mechanistic insights we investigated the predicted amino acid substitutions mediated by readthrough (W209C/R, C56W/R), which resulted in correct lysosomal localization and appreciable protein/activity levels for the W209C/R variants. Differently, the C56W/R variants, albeit appreciably produced and localized into lysosomes, were inactive, thus indicating detrimental effects of substitutions at this position.Noticeably, when co-expressed with the functional W209C or W209R variants, the wild-type rGal displayed a reduced specific activity (0.5 ± 0.2 and 0.6 ± 0.2, respectively) that, considering the dimeric features of the α-Gal enzyme, suggested dominant-negative effects of missense variants through their interaction with the wild-type.Overall, we provide a novel mechanism through which amino acids inserted during readthrough might impact on the functional protein output. Our findings may also have implications for the interpretation of pathological phenotypes in heterozygous FD females, and for other human disorders involving dimeric or oligomeric proteins.
Collapse
Affiliation(s)
- Silvia Lombardi
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy
| | - Mattia Ferrarese
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy
| | - Saverio Marchi
- Department of Morphology, Surgery and Experimental Medicine, Section of Pathology, Oncology and Experimental Biology, University of Ferrara, Ferrara, Italy
| | - Paolo Pinton
- Department of Morphology, Surgery and Experimental Medicine, Section of Pathology, Oncology and Experimental Biology, University of Ferrara, Ferrara, Italy
| | - Mirko Pinotti
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy
| | - Francesco Bernardi
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy
| | - Alessio Branchini
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy
| |
Collapse
|
12
|
Balestra D, Maestri I, Branchini A, Ferrarese M, Bernardi F, Pinotti M. An Altered Splicing Registry Explains the Differential ExSpeU1-Mediated Rescue of Splicing Mutations Causing Haemophilia A. Front Genet 2019; 10:974. [PMID: 31649737 PMCID: PMC6796300 DOI: 10.3389/fgene.2019.00974] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Accepted: 09/12/2019] [Indexed: 12/12/2022] Open
Abstract
The exon recognition and removal of introns (splicing) from pre-mRNA is a crucial step in the gene expression flow. The process is very complex and therefore susceptible to derangements. Not surprisingly, a significant and still underestimated proportion of disease-causing mutations affects splicing, with those occurring at the 5’ splice site (5’ss) being the most severe ones. This led to the development of a correction approach based on variants of the spliceosomal U1snRNA, which has been proven on splicing mutations in several cellular and mouse models of human disease. Since the alternative splicing mechanisms are strictly related to the sequence context of the exon, we challenged the U1snRNA-mediated strategy in the singular model of the exon 5 of coagulation factor (F)VIII gene (F8) in which the authentic 5’ss is surrounded by various cryptic 5’ss. This scenario is further complicated in the presence of nucleotide changes associated with FVIII deficiency (Haemophilia A), which weaken the authentic 5’ss and create/strengthen cryptic 5’ss. We focused on the splicing mutations (c.602-32A > G, c.602-10T > G, c.602G > A, c.655G > A, c.667G > A, c.669A > G, c.669A > T, c.670G > T, c.670+1G > T, c.670+1G > A, c.670+2T > G, c.670+5G > A, and c.670+6T > C) found in patients with severe to mild Haemophilia A. Minigenes expression studies demonstrated that all mutations occurring within the 5’ss, both intronic or exonic, lead to aberrant transcripts arising from the usage of two cryptic intronic 5’ss at positions c.670+64 and c.670+176. For most of them, the observed proportion of correct transcripts is in accordance with the coagulation phenotype of patients. In co-transfection experiments, we identified a U1snRNA variant targeting an intronic region downstream of the defective exon (Exon Specific U1snRNA, U1sh7) capable to re-direct usage of the proper 5’ss (∼80%) for several mutations. However, deep investigation of rescued transcripts from +1 and +2 variants revealed only the usage of adjacent cryptic 5’ss, leading to frameshifted transcript forms. These data demonstrate that a single ExSpeU1 can efficiently rescue different mutations in the F8 exon 5, and provide the first evidence of the applicability of the U1snRNA-based approach to Haemophilia A.
Collapse
Affiliation(s)
- Dario Balestra
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy
| | - Iva Maestri
- Department of Experimental and Diagnostic Medicine, University of Ferrara, Ferrara, Italy
| | - Alessio Branchini
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy
| | - Mattia Ferrarese
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy
| | - Francesco Bernardi
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy
| | - Mirko Pinotti
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy
| |
Collapse
|
13
|
Fazzari M, Frasca A, Bifari F, Landsberger N. Aminoglycoside drugs induce efficient read-through of CDKL5 nonsense mutations, slightly restoring its kinase activity. RNA Biol 2019; 16:1414-1423. [PMID: 31232219 PMCID: PMC6779400 DOI: 10.1080/15476286.2019.1632633] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Revised: 05/23/2019] [Accepted: 06/06/2019] [Indexed: 10/26/2022] Open
Abstract
The X-linked CDKL5 gene codes for a kinase whose mutations have been associated with a suite of neurodevelopmental disorders generally characterized by early-onset epileptic encephalopathy and severe intellectual disability. The impact of these mutations on CDKL5 functions and brain development remain mainly unknown, although the importance of maintaining the catalytic activity is generally recognized. Since no cure exists for CDKL5 disorders, the demand for innovative therapies is a real emergency. The recent discovery that CDKL5 is dosage sensitive poses concerns on conventional protein and gene augmentative therapies. Thus, RNA-based therapeutic approaches might be preferred. We studied the efficacy of read-through therapy on CDKL5 premature termination codons (PTCs) that correspond roughly to 15% of all mutations. Our results provide the first demonstration that all tested CDKL5 nonsense mutations are efficiently suppressed by aminoglycoside drugs. The functional characterization of the restored full-length CDKL5 reveals that read-through proteins fully recover their subcellular localization, but only partially rescue their catalytic activity. Since read-through can cause amino acid substitution, CDKL5 patients carrying the PTC outside the catalytic domain might benefit more from a nonsense suppression therapy. Eventually, we demonstrate that non-aminoglycoside drugs, such as Ataluren (PTC124) and GJ072, are unable to induce read-through activity on CDKL5 PTCs. Although these drugs might be more effective in vivo, these results question the validity of the Ataluren phase 2 clinical trial that is currently ongoing on CDKL5 patients.
Collapse
Affiliation(s)
- Maria Fazzari
- Department of Medical Biotechnology and Translational Medicine, University of Milan, Segrate, Italy
| | - Angelisa Frasca
- Department of Medical Biotechnology and Translational Medicine, University of Milan, Segrate, Italy
| | - Francesco Bifari
- Department of Medical Biotechnology and Translational Medicine, University of Milan, Segrate, Italy
| | - Nicoletta Landsberger
- Department of Medical Biotechnology and Translational Medicine, University of Milan, Segrate, Italy
| |
Collapse
|
14
|
Ferraresi P, Balestra D, Guittard C, Buthiau D, Pan-Petesh B, Maestri I, Farah R, Pinotti M, Giansily-Blaizot M. Next-generation sequencing and recombinant expression characterized aberrant splicing mechanisms and provided correction strategies in factor VII deficiency. Haematologica 2019; 105:829-837. [PMID: 31273093 PMCID: PMC7049351 DOI: 10.3324/haematol.2019.217539] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Accepted: 07/02/2019] [Indexed: 01/22/2023] Open
Abstract
Despite the exhaustive screening of F7 gene exons and exon-intron boundaries and promoter region, a significant proportion of mutated alleles remains unidentified in patients with coagulation factor VII deficiency. Here, we applied next-generation sequencing to 13 FVII-deficient patients displaying genotype-phenotype discrepancies upon conventional sequencing, and identified six rare intronic variants. Computational analysis predicted splicing effects for three of them, which would strengthen (c.571+78G>A; c.806-329G>A) or create (c.572-392C>G) intronic 5′ splice sites (5′ss). In F7 minigene assays, the c.806-329G>A was ineffective while the c.571+78G>A change led to usage of the +79 cryptic 5′ss with only trace levels of correct transcripts (3% of wild-type), in accordance with factor VII activity levels in homozygotes (1-3% of normal). The c.572-392C>G change led to pseudo-exonization and frame-shift, but also substantial levels of correct transcripts (approx. 70%). However, this variant was associated with the common F7 polymorphic haplotype, predicted to further decrease factor VII levels; this provided some kind of explanation for the 10% factor VII levels in the homozygous patient. Intriguingly, the effect of the c.571+78G>A and c.572-392C>G changes, and particularly of the former (the most severe and well-represented in our cohort), was counteracted by antisense U7snRNA variants targeting the intronic 5′ss, thus demonstrating their pathogenic role. In conclusion, the combination of next-generation sequencing of the entire F7 gene with the minigene expression studies elucidated the molecular bases of factor VII deficiency in 10 of 13 patients, thus improving diagnosis and genetic counseling. It also provided a potential therapeutic approach based on antisense molecules that has been successfully exploited in other disorders.
Collapse
Affiliation(s)
- Paolo Ferraresi
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy
| | - Dario Balestra
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy
| | - Caroline Guittard
- Department of Biological Haematology, CHU Montpellier, Université Montpellier, Montpellier, France
| | - Delphine Buthiau
- Department of Biological Haematology, CHU Montpellier, Université Montpellier, Montpellier, France
| | | | - Iva Maestri
- Department of Morphology, Surgery and Experimental Medicine, University of Ferrara, Ferrara, Italy
| | - Roula Farah
- Department of Pediatrics, Saint George Hospital University Medical Center, Beirut, Lebanon
| | - Mirko Pinotti
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy
| | - Muriel Giansily-Blaizot
- Department of Biological Haematology, CHU Montpellier, Université Montpellier, Montpellier, France
| |
Collapse
|
15
|
Balestra D, Branchini A. Molecular Mechanisms and Determinants of Innovative Correction Approaches in Coagulation Factor Deficiencies. Int J Mol Sci 2019; 20:ijms20123036. [PMID: 31234407 PMCID: PMC6627357 DOI: 10.3390/ijms20123036] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2019] [Revised: 06/07/2019] [Accepted: 06/18/2019] [Indexed: 02/07/2023] Open
Abstract
Molecular strategies tailored to promote/correct the expression and/or processing of defective coagulation factors would represent innovative therapeutic approaches beyond standard substitutive therapy. Here, we focus on the molecular mechanisms and determinants underlying innovative approaches acting at DNA, mRNA and protein levels in inherited coagulation factor deficiencies, and in particular on: (i) gene editing approaches, which have permitted intervention at the DNA level through the specific recognition, cleavage, repair/correction or activation of target sequences, even in mutated gene contexts; (ii) the rescue of altered pre-mRNA processing through the engineering of key spliceosome components able to promote correct exon recognition and, in turn, the synthesis and secretion of functional factors, as well as the effects on the splicing of missense changes affecting exonic splicing elements; this section includes antisense oligonucleotide- or siRNA-mediated approaches to down-regulate target genes; (iii) the rescue of protein synthesis/function through the induction of ribosome readthrough targeting nonsense variants or the correction of folding defects caused by amino acid substitutions. Overall, these approaches have shown the ability to rescue the expression and/or function of potentially therapeutic levels of coagulation factors in different disease models, thus supporting further studies in the future aimed at evaluating the clinical translatability of these new strategies.
Collapse
Affiliation(s)
- Dario Balestra
- Department of Life Sciences and Biotechnology, University of Ferrara, 44121 Ferrara, Italy.
| | - Alessio Branchini
- Department of Life Sciences and Biotechnology, University of Ferrara, 44121 Ferrara, Italy.
| |
Collapse
|
16
|
Liu Z, Zhang Y, Zhu M, Zhang B. Identification of candidate nonsense mutations of FVIII for ribosomal readthrough therapy. Haematologica 2019; 104:e573-e576. [PMID: 31004034 DOI: 10.3324/haematol.2018.205104] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Affiliation(s)
- Zhigang Liu
- Genomic Medicine Institute, Cleveland Clinic Lerner Research Institute, Cleveland, OH, USA and
| | - Yuan Zhang
- Genomic Medicine Institute, Cleveland Clinic Lerner Research Institute, Cleveland, OH, USA and
| | - Min Zhu
- Genomic Medicine Institute, Cleveland Clinic Lerner Research Institute, Cleveland, OH, USA and .,Department of Pathology, Karamay Central Hospital, Karamay, China
| | - Bin Zhang
- Genomic Medicine Institute, Cleveland Clinic Lerner Research Institute, Cleveland, OH, USA and
| |
Collapse
|
17
|
Ferrarese M, Baroni M, Della Valle P, Spiga I, Poloniato A, D'Angelo A, Pinotti M, Bernardi F, Branchini A. Missense changes in the catalytic domain of coagulation factor X account for minimal function preventing a perinatal lethal condition. Haemophilia 2019; 25:685-692. [PMID: 30994257 DOI: 10.1111/hae.13761] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 03/23/2019] [Accepted: 03/23/2019] [Indexed: 11/26/2022]
Abstract
INTRODUCTION Inherited deficiencies in the coagulation pathway provide diversified models to investigate the molecular bases of perinatal lethality associated with null-like variants. Differently from X-linked haemophilias, homozygous/doubly heterozygous null variants in the rare autosomally inherited deficiency of factor X (FX) might be incompatible with perinatal survival. AIM To provide experimental evidence about the null/close-to-null FX function. METHODS The residual secreted (ELISA) and functional (thrombin generation assays) protein levels associated with the novel nonsense (c.1382G>A; p.Trp461Ter) and missense (c.752T>C; p.Leu251Pro) variants, found in the proposita with life-threatening symptoms at birth, were characterized through recombinant (r)FX expression. RESULTS The rFX-461Ter showed very low secretion and undetectable function. Expression and function of the predicted readthrough-deriving missense variants (rFX-461Tyr, rFX-461Gln) were also severely impaired. These unfavourable features, due to nucleotide and protein sequence constraints, precluded functional readthrough over the 461 stop codon. Differently, the poorly secreted rFX-251Pro variant displayed residual function that was characterized by anti-TFPI aptamer-based amplification or selective inhibition of activated FX function by fondaparinux in plasma and found to be reduced by approximately three orders of magnitude. Similarly to the rFX-251Pro, a group of catalytic domain missense variants cause poorly secreted molecules with modest function in FX-deficient patients with life-threatening symptoms. CONCLUSIONS Our data, contributing to the knowledge of the very severe FX deficiency forms, support life-saving requirement of trace FX function, clearly exemplified by the dysfunctional but not completely inactive rFX-251Pro variant that, albeit with severely reduced function, is compatible with a residual activity ensuring minimal haemostasis and permitting perinatal survival.
Collapse
Affiliation(s)
- Mattia Ferrarese
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy
| | - Marcello Baroni
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy
| | - Patrizia Della Valle
- Coagulation Service and Thrombosis Research Unit, San Raffaele Scientific Institute, Milan, Italy
| | - Ivana Spiga
- Clinical Molecular Biology Laboratory, IRCCS San Raffaele Hospital, Milan, Italy
| | - Antonella Poloniato
- Neonatology Unit, Mother-Child Department, IRCCS San Raffaele Hospital, Milan, Italy
| | - Armando D'Angelo
- Coagulation Service and Thrombosis Research Unit, San Raffaele Scientific Institute, Milan, Italy
| | - Mirko Pinotti
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy
| | - Francesco Bernardi
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy
| | - Alessio Branchini
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy
| |
Collapse
|
18
|
Pignani S, Todaro A, Ferrarese M, Marchi S, Lombardi S, Balestra D, Pinton P, Bernardi F, Pinotti M, Branchini A. The chaperone-like sodium phenylbutyrate improves factor IX intracellular trafficking and activity impaired by the frequent p.R294Q mutation. J Thromb Haemost 2018; 16:2035-2043. [PMID: 29993188 DOI: 10.1111/jth.14236] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Indexed: 12/25/2022]
Abstract
Essentials Missense mutations often impair protein folding, and thus intracellular trafficking and secretion. Cellular models of severe type I hemophilia B were challenged with chaperone-like compounds. Sodium phenylbutyrate improved intracellular trafficking and secretion of the frequent p.R294Q. The increased coagulant activity levels (∼3%) of p.R294Q would ameliorate the bleeding phenotype. SUMMARY Background Missense mutations often impair protein folding and intracellular processing, which can be improved by small compounds with chaperone-like activity. However, little has been done in coagulopathies, where even modest increases of functional levels could have therapeutic implications. Objectives To rescue the expression of factor IX (FIX) variants affected by missense mutations associated with type I hemophilia B (HB) through chaperone-like compounds. Methods Expression studies of recombinant (r)FIX variants and evaluation of secreted levels (ELISA), intracellular trafficking (immunofluorescence) and activity (coagulant assays) before and after treatment of cells with chaperone-like compounds. Results As a model we chose the most frequent HB mutation (p.R294Q, ~100 patients), compared with other recurrent mutations associated with severe/moderate type I HB. Immunofluorescence studies revealed retention of rFIX variants in the endoplasmic reticulum and negligible localization in the Golgi, thus indicating impaired intracellular trafficking. Consistently, and in agreement with coagulation phenotypes in patients, all missense mutations resulted in impaired secretion (< 1% wild-type rFIX). Sodium phenylbutyrate (NaPBA) quantitatively improved trafficking to the Golgi and dose dependently promoted secretion (from 0.3 ± 0.1% to 1.5 ± 0.3%) only of the rFIX-294Q variant. Noticeably, this variant displayed a specific coagulant activity that was higher (~2.0 fold) than that of wild-type rFIX in all treatment conditions. Importantly, coagulant activity was concurrently increased to levels (3.0 ± 0.9%) that, if achieved in patients, would ameliorate the bleeding phenotype. Conclusions Altogether, our data detail molecular mechanisms underlying type I HB and candidate NaPBA as affordable 'personalized' therapeutics for patients affected by the highly frequent p.R294Q mutation, and with reduced access to substitutive therapy.
Collapse
Affiliation(s)
- S Pignani
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy
| | - A Todaro
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy
| | - M Ferrarese
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy
| | - S Marchi
- Department of Morphology, Surgery and Experimental Medicine, Section of Pathology, Oncology and Experimental Biology, University of Ferrara, Ferrara, Italy
| | - S Lombardi
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy
| | - D Balestra
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy
| | - P Pinton
- Department of Morphology, Surgery and Experimental Medicine, Section of Pathology, Oncology and Experimental Biology, University of Ferrara, Ferrara, Italy
| | - F Bernardi
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy
| | - M Pinotti
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy
| | - A Branchini
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy
| |
Collapse
|